Journal of the American Oil Chemists' Society

, Volume 90, Issue 3, pp 327–335 | Cite as

Analysis of CLA Isomer Distribution in Nutritional Supplements by Single Column Silver-Ion HPLC

  • L. Cossignani
  • L. Giua
  • G. Lombardi
  • M. S. Simonetti
  • P. Damiani
  • F. Blasi
Original Paper


Nutritional supplements containing conjugated linoleic acid (CLA) isomers, widely used to improve body composition and inhibit fat storage, should be thoroughly analyzed, as CLA effects are isomer specific. In this research, an improvement of silver-ion high performance liquid chromatography (Ag+-HPLC) was obtained by using a single-column instead of the most commonly used multi-columns. To develop the procedure, a standard CLA mixture has been derivatized with different chain length alcohols (from methanol to hexanol). Hexyl CLA showed better separation between CLA isomer pairs, in particular the resolution of the t10,c12: c9,t11 pair increased from 0.3 (methyl esters) to 0.8 (hexyl esters). Therefore, the CLA isomer composition of some commercial CLA products was determined by Ag+-HPLC analysis of hexyl esters. The main isomers in all supplements turned out to be c9,t11-CLA and t10,c12-CLA, the most anti-adipogenic isomer. t8,c10- and c11,t13-CLA were not detected. The nutritional supplements were also analyzed by high resolution gas chromatography of methyl esters to evaluate the fatty acid % composition and total CLA % content. The total CLA ranged from 79.4 to 94.4 %, and the t,t isomer from 1.4 to 7.3 %.


Nutritional supplements Conjugated linoleic acid Hexyl esters Ag+-HPLC HRGC 


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Copyright information

© AOCS 2012

Authors and Affiliations

  • L. Cossignani
    • 1
  • L. Giua
    • 1
  • G. Lombardi
    • 1
  • M. S. Simonetti
    • 1
  • P. Damiani
    • 1
  • F. Blasi
    • 1
  1. 1.Dipartimento di Scienze Economico-Estimative e degli Alimenti, Sezione di Chimica Bromatologica, Biochimica, Fisiologia e NutrizioneUniversità degli Studi di PerugiaPerugiaItaly

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